1. Field of the Invention
The present invention relates to a method and a system for broadcasting data to users through a multiplicity of addressed broadcasting channels.
2. Discussion of the Background
In the state of the art, data from one or more servers in a telecommunications network, in particular multimedia data, are transmitted to the users either in pull mode or in push mode. In pull mode, the data remain stored in the server until a user downloads them in a terminal via a telecommunications network. This type of transmission thus requires the active participation of the user, who has to search for the necessary data himself and decide which information he would like to receive.
This active search is only possible, however, if the data are transmitted over a bidirectional telecommunications network, for example over the public telephone network. Furthermore, a minimum amount of computer science knowledge and a not insignificant expenditure of time is required to find relevant data.
In the push mode (broadcasting), the data are transmitted from a server to all user terminals at the same time, which terminals receive these data passively. Depending upon channel type, these data can either be filtered and temporarily stored in the terminal of the user or can be shown immediately or passed on. Most broadcasting systems are purely monodirectional and therefore have no backward channel by means of which the user can reply to the transmitter. That is the case, for example, in the common radio and television broadcasting systems. If the recipient, for example the radio listener or the television viewer, would like to react to a broadcast or to a commercial, he therefore has to access another telecommunications system, for example his telephone. This procedure is extremely inconvenient and error-prone. The common broadcasting systems are thus only partially suitable for motivating users to make spontaneous purchases during or immediately after a commercial. The teletext system or DAB (Digital Audio Broadcasting) system can be mentioned, for example, as digital broadcasting channels.
Bidirectional push channels have recently come into being which have a supplementary backward channel. In particular, multimedia data are being transmitted more and more frequently via the Internet in push mode. In this case the users can reply to the information suppliers by e-mail.
In the usual push systems, the same, entire program is transmitted to all users from one or more servers. Each user terminal in this case includes a filter by means of which only that data which interest the user are stored or displayed. For example, if a complete information program is transmitted to a recipient, he decides to store or display only the information on sports or politics. Use of the bandwidth of the channel is thus not optimal: data are transmitted also to users who are not interested in them. Moreover the users have to wait until the information they are interested in is sent.
The usual data broadcasting systems are dependent upon a particular broadcasting channel. The user must therefore be equipped with a suitable terminal in order to be able to access the information of a particular information supplier. The user generally does not have the possibility, however, of selecting a terminal of any desired type in order to access the data of a particular information supplier. Vice-versa, the information supplier cannot easily broadcast his collection of information through different broadcasting channels.
In the printed patent specification U.S. Pat. No. 5,592,626, a network system is described for the transmission of multimedia programs to a multiplicity of users, the transmission taking place at points in time specified beforehand by the users. According to the teaching of U.S. Pat. No. 5,592,626, the transmission times specified by the users are received by a scheduler, who established in each case a network server path via which a multimedia program selected by a respective user is transmitted efficiently and at the specified point in time to the respective user, the network servers receiving the multimedia programs, temporarily storing them in a cache memory, and passing them on directly to a respective user or to a further network server.
Described in the patent application WO 98/03928 is a web server system which receives digital documents, for example e-mail messages or fax messages, from respective terminals, converts the received digital documents into documents of HTML format (hypertext markup language) and stores the HTML documents in a data base, which can be looked at by users via the Internet, the HTML documents being transmitted to the users over the Internet.